Help with large guest list for our upcoming wedding?

My fiance proposed to me back in October and we've been planning our wedding from that point on. We have our guest list pretty set now, but it's insanely large for what we originally planned. We are preparing to send out our save-the-dates this weekend. Should we address the save-the-dates with the person and their guest? Or just to the person we're inviting? I know these are not the same as the actual invitations, so I wasn't sure. Also, how can we cut guests that people bring? Like, some of my family have boyfriends/girlfriends that they either have been dating for a long time or just recently started dating. Should we include those significant others names on the save-the-dates? Thank you for your helpful feedback.